Throughout the specification and claims, the term "I.C." is to be understood to relate to an "internal combustion engine", while "A/F" is to be understood to means "air to fuel ratio". The term "signal" relates to a current or voltage pulse of any suitable value and wave form which is compatible with the teachings of this invention.
Pollution of our environment with exhaust emissions from internal combustion engines is considered to be a primary health hazard, and for this reason great emphasis is presently being placed upon the provision of means approaching complete combustion of hydrocarbon fuels to thereby lower undesirable or hazardous exhaust emissions to a minimum. Modern electronic technology provides vastly improved means by which the A/F ratio of the gaseous mixture contained within combustion chambers can be maintained at a predetermined value in a manner which is far superior to mechanical carburetors of the prior art. For example, Mycroft, U.S. Pat. Nos. 3,470,858; Westbrook et al, 3,272,187; and Wallis, 3,240,191 propose various systems for more closely controlling the A/F ratio in internal combustion engines, and to which reference is made for further background of this invention.
In these and other prior art systems for controlling A/F ratio, the air flow rate generally has been utilized to influence the fuel flow rate, with mechanical provision be made for warm-up enrichment, acceleration enrichment, as well as for temperature and barometric changes. However, once the fuel flow rate demanded by a particular instantaneous mass air flow rate has been determined by the prior art electronic circuitry, control over the system is generally left to chance, and as may be expected, variations in the system downstream of the controlling sensor means inherently changes a sufficient amount to render all of the previous control work inefficient.
Therefore, it is desirable to provide an improved electronic carburetion system for controlling the A/F to an I.C. engine, and to positively measure the fuel flow rate from the fuel pump so as to enable comparison of the actual fuel flow rate to be made with the measured mass air flow rate, thereby enabling further correction means to be employed as the ratio therebetween changes from a predetermined ideal value.